After testing all of our graphics cards using a stock Core i7-3960X, with its six cores and Hyper-Threading technology enabled, we swapped in a range of lower-end processors and platforms to compare.
The Sandy Bridge-E-based Core i7 easily beats the Ivy Bridge-based Core i5-3550 and Vishera-based FX-8350, which both achieve about 50 FPS, on average. Unfortunately for AMD, its CPU dips to 21 FPS, while the Core i5 maintains at least 31 FPS.
As for the Core i3, Pentium, Phenom II X4, and quad-core A8 APU, none maintains more than a 20 FPS minimum frame rate at the High detail preset.
Thinking that this might have been an avoidable bottleneck caused by our detail settings, we dropped the preset to Low and re-tested the Phenom II X4 and Core i3-3220. Even then, we didn't see minimums any higher than 25 FPS. The issue wasn't fixed in the recent 1.2 patch, either.
Our benchmark sequence does have that taxing bottleneck at the end of the run. But no matter how you process the data, processor performance is going to be an important consideration in Crysis 3. We can't recommend anything less than a Core i5 to gamers building a PC capable of handling this game, and serious enthusiasts will want a Core i7. Crysis 3 appears to be one of those rare games optimized for multi-core processors, as evidenced by the six-core Sandy Bridge-E's strong result compared to quad-core Ivy Bridge.
Having said that, AMD's FX-8350 provides serviceable Crysis 3 game play. Despite the frame rate valley we experienced in our benchmark run, this CPU achieves smoother performance on average. Perhaps this is something Crytek will be able to address through a future update.